1. Field of the Invention
The present invention relates to golf ball core materials. More specifically, the present invention relates to thermoplastic polyester elastomer golf ball cores.
2. Description of the Related Art
When used in golf balls, injection moldable thermoplastic elastomers (TPE) offer significant economic advantages over thermoset polymer systems. This is especially true for golf ball cores where compression molded polybutadiene thermoset systems are typically used. Relatively low conversion costs make TPEs very attractive alternatives to thermoset systems.
Thermoplastic polyester elastomers (TPEE) in particular are well suited for use in golf ball cores. Relative to thermoplastic polyamide elastomers and most thermoplastic polyurethane elastomers, they exhibit high levels of rebound resilience. Relative to ionomers they have a high density reducing the need for modification with high density fillers. Common trade names for these materials include Hytrel from DuPont and Arnitel from DSM.
While TPEEs typically have high rebound resilience, they aren't resilient enough for use in some higher compression golf ball core applications. In addition, they don't quite match the rebound resilience of ionomeric thermoplastic elastomers. This is especially true for higher modulus formulations.
Sullivan et al., U.S. Pat. No. 4,911,451, for a Golf Ball Cover Of Neutralized Poly(ethylene-acrylic acid) Copolymer, discloses in Table One a golf ball having a compression of below 50 and a cover composed of ionomers having various Shore D hardness values ranging from 50 to 61.
Sullivan, U.S. Pat. No. 4,986,545, for a Golf Ball discloses a golf ball having a Rhiele compression below 50 and a cover having Shore C values as low as 82.
Egashira et al., U.S. Pat. No. 5,252,652, for a Solid Golf Ball, discloses the use of a zinc pentachlorothiophenol in a core of a golf ball.
Pasqua, U.S. Pat. No. 5,721,304, for a Golf Ball Composition, discloses a golf ball with a core having a low compression and the core comprising calcium oxide.
Sullivan, et al., U.S. Pat. No. 5,588,924, for a Golf Ball discloses a golf ball having a PGA compression below 70 and a COR ranging from 0.780 to 0.825.
Sullivan et al., U.S. Pat. No. 6,142,886, for a Golf Ball And Method Of Manufacture discloses a golf ball having a PGA compression below 70, a cover Shore D hardness of 57, and a COR as high as 0.794.
Tzivanis et al., U.S. Pat. No. 6,520,870, for a Golf Ball, discloses a golf ball having a core compression less than 50, a cover Shore D hardness of 55 or less, and a COR greater than 0.80.
The prior art fails to disclose a multiple layer golf ball with a multiple layer core that have high rebound resilience.